Generally, an Electronic Service Guide (ESG) enables a terminal to communicate what services are available to end users and how the services may be accessed. ESG fragments are independently existing pieces of the ESG. Traditionally, ESG fragments comprise XML documents, but more recently they have encompassed a vast array of items, such as for example, a SDP (Session Description Protocol) description, textual file, or an image. The ESG fragments describe one or several aspects of currently available (or future) service or broadcast program. Such aspects may include for example: free text description, schedule, geographical availability, price, purchase method, genre, and supplementary information such as preview images or clips. Audio, video and other types of data comprising the ESG fragments may be transmitted through a variety of types of networks according to many different protocols. For example, data can be transmitted through a collection of networks usually referred to as the “Internet” using protocols of the Internet protocol suite, such as Internet Protocol (IP) and User Datagram Protocol (UDP). Data is often transmitted through the Internet addressed to a single user. It can, however, be addressed to a group of users, commonly known as multicasting. In the case in which the data is addressed to all users it is called broadcasting. The ESG data may be transmitted using different types of wireless digital networks including digital broadband broadcast and/or multicast networks.
ESG fragments may be instantiated using a syntax such as XML and may include content including metadata and descriptions of services. Typically, the content of the ESG fragment does not provide information indicating the identity of the contents. Hence, when a subscriber terminal receives the ESG fragment, the subscriber terminal does not deduce the contents of the ESG fragment. For example, the subscriber terminal does not have information regarding the organization of the content in the ESG fragment or an indication of how the content of the ESG fragment may be retrieved. Also, the subscriber terminal does not have information regarding the specific content. Due to this lack of information, the subscriber terminal may not know what ESG fragment data it already has and may thus re-store data that it already has. This leads to a waste of resources.
Thus, there exists a need for a method and system for identifying the content of ESG fragments in an efficient manner. There is also a need for a method and system in which a subscriber terminal may receive information, such as organization of content in an ESG fragment so that retrieval of data in the ESG fragment can be optimized.